An apparatus for mounting electronic components on a circuit board or a substrate is already known, which comprises an electronic components feeding device, an X-Y table for positioning the circuit board, and a rotary head furnished with pick-and-place heads for mounting the electronic components on the board. The electronic components feeding device comprises tables, where the feeders of the components are mounted, and a moving base for moving the tables in lateral direction.
The electronic components mounting apparatus as described above picks up the components from the feeders and mounts them on the circuit board, which is positioned on an X-Y table when the pick-and-place heads are rotated for indexing along the rotary head.
Further, a multi-table electronic components feeding device with a plurality of tables has been proposed (Japanese Patent Laid-Open Publication No. 300598/1989). Such multi-table feeding device independently moves each of the tables in lateral direction and it is advantageous in that the feeders can be readily exchanged when there is no more electronic component on the feeders.
With the increasing demand on quick and speedier mounting of electronic components in recent years, the moving speed of the above tables must be increased to achieve the mounting in speedy manner. The tables must be stopped at proper position so that the desired feeder stops at the correct pickup position on the pick-and-place heads. However, when the moving speed of the table is increased, the tables may be vibrated when they are stopped, and it is difficult to stop the feeder at the correct pickup position. Because the types of the electronic components to be mounted on the circuit board are increasing and are more diversified, the number of the feeders is also increasing. In some cases, 150 or more feeders must be placed on a table, and the total weight of the table will be 200 kg or more. When such a weighty table is moved at high speed and is stopped suddenly, the table is vibrated extremely. Also, it cannot be started quickly because of inertia when it is stopped.
To solve the above problems, it has been proposed to divide the table into as many tables as possible, turning it to a multi-table. In such a multi-table system, the weight of the table is light, and the moving inertia and the stopping inertia are decreased. Thus, it is possible to move the table at high speed.
However, moving means are required for each of these tables if they are designed in multi-table system, and this means that a large size apparatus is required. Ball screws and nuts or linear motor are used as the moving means, while ball screws, nuts and linear motors are very expensive because high molding accuracy is required. If these are used as the moving means for each of the tables, the manufacturing cost for the electronic components feeding device will be extremely expensive.